Okay. First of all you have to admit to yourself you probably are eating to much. You may not realize it but you are. There is no possible way to get fat without taking in more calories than you are using. Its a maths/science thing (trust me, if people could eat less calories than they use and get fat they would study you to beat famines around the world)
Burning more calories doesnt mean exercise that impacts you in anyway, it just means raising your heart rate as much as you can for a period of time. For now i would just log your calories on a website such as fitday.com or similar to find out how many you are eating and where they are comming from.
Depending on the size of the patties they could be about 300 calories each if decent sized which means thats 600 calories of patty, plus a soda is 200 per can so thats maybe 1000 more, plus whatever sugar in the coffee, cookie, or whatever else. It may be a small amount of food, but its super high in calories.
This doesnt mean you have to give up that food, just be aware that having 1 whole hambuger with bun and salad and 1 patty in the burger would be a whole lot more filling and better than just the 2 patties. And a diet soda is pretty much 0 calories which alone would probably save you a fair few
